fix: Add support for customizable tree key in SelectTree

Introduce a `treeKey` property and associated methods to allow customization of the tree identifier. Updated Blade template to use the specified tree key for the `wire:key` attribute to ensure predictable component rendering.

This is to address issue #141.

Author: mgkimsal

resources/views/select-tree.blade.php

@@ -12,7 +12,7 @@
 
 <x-dynamic-component :component="$getFieldWrapperView()" :field="$field">
     <div
-        wire:key="{{ rand() }}"
+        wire:key="{{ $getTreeKey() }}"
         wire:ignore
         x-ignore
         @if (FilamentView::hasSpaMode())

src/SelectTree.php

@@ -88,6 +88,8 @@ class SelectTree extends Field implements HasAffixActions
 
     protected Closure|array|null $prepend = null;
 
+    protected Closure|string|null $treeKey = 'defaultTreeKey';
+
     protected function setUp(): void
     {
         // Load the state from relationships using a callback function.
@@ -614,4 +616,16 @@ public function createOptionModalHeading(string|Closure|null $heading): static
 
         return $this;
     }
+
+    public function treeKey(string $treeKey): static
+    {
+        $this->treeKey = $treeKey;
+
+        return $this;
+    }
+
+    public function getTreeKey(): string
+    {
+        return $this->evaluate($this->treeKey);
+    }
 }